In a direct conversion transmitter, if an oscillating frequency of an oscillator of when generating a local signal and a frequency of an output signal of a power amplifier are in a relationship of being the same or integral multiples, the noise corresponding to the output signal of the power amplifier may influence the operation of the oscillator. In this case, the local signal may distort and the modulation accuracy in a mixer may degrade. With regards thereto, it is proposed to pass the output of the oscillator through a fractional frequency dividing circuit to generate a local signal, and to have the oscillating frequency of the oscillator and the frequency of the output signal of the power amplifier in a fractional relationship. In this case, it is desired to reduce the unnecessary tone with a simple configuration.